Can you please explain how you managed to get it working with full QE/CI under 10.5.2 ??
Mine was good until I updated everything to 10.5.2 ...
Tried everything since then but no luck ... Please tell us how you did it ...

Yup, same problem here
Got a Sapphine x1600pro 512MB and still cant get it to work properly.
I used 10.5.1 and edited the ATIRadeonX1000.kext, everything worked perfect! except for the occasional screen freezes... Now that I got 10.5.2 nothing worx and I`m getting frustrated like hell!
Is there anyone who can help us? I got everything else working on my machine, but with no full graphics it all sux!!
Is there a way to get this card working properly on 10.5.2?